[ALSA] ASoC at91 - Fix NULL pointer dereference in at91_i2s_shutdown

This patch fixes a NULL pointer exception which occurs when a
substream is opened and immediately closed.

Signed-off-by: Frank Mandarino <fmandarino@endrelia.com>
Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

1 files changed, 7 insertions, 0 deletions

diff --git a/sound/soc/at91/at91-i2s.c b/sound/soc/at91/at91-i2s.c
index 203e6948cd99..876d391c7013 100644
--- a/sound/soc/at91/at91-i2s.c
+++ b/sound/soc/at91/at91-i2s.c
@@ -296,6 +296,13 @@ static int at91_i2s_startup(struct snd_pcm_substream *substream)
         ssc_p->dir_mask |= dir_mask;
         spin_unlock_irq(&ssc_p->lock);
 
+        /*
+         * dma_data is not set until hw_params() is called and
+         * shutdown() depends on this value being NULL if hw_params()
+         * was not called.
+         */
+        rtd->cpu_dai->dma_data = NULL;
+
         return 0;
 }